The meninges are the protective triple-layered membranes that surround the brain and spinal cord. The three layers are the dura mater, arachnoid mater, and pia mater. The dura mater is the outermost layer, while the pia mater closely adheres to the brain and spinal cord. Between the arachnoid mater and pia mater is the subarachnoid space, which contains cerebrospinal fluid (CSF). CSF circulates through the brain ventricles and subarachnoid space, carrying nutrients and protecting the central nervous system.

1. MENINGES AND CSF
Prepared By: Ms. Simranjeet Kaur

2. CNS
• The CNS consists of the brain and spinal cord.
• The brain is protected by the skull (the cranial cavity) and the spinal cord travels
from the back of the brain, down the center of the spine, stopping in the lumbar
region of the lower back.
• The brain and spinal cord are both housed within a protective triple-layered
membrane called the meninges.

3. Meninges
• The meninges are the connective tissue
coverings that encircle the spinal cord
and brain.
• The spinal meninges surround the spinal
cord and are continuous with the cranial
meninges, which encircle the brain.
• Meninges are of three types:
 Dura Mater
 Pia Mater
 Menix ( Arachnoid Mater)

4. Dura mater
• It is the outermost of the three layers of the
meninges surrounding the brain and spinal
cord
• Dura mater has two layers:
• The superficial layer, which serves as the
skull's inner periosteum; (periosteal layer)
• The deep layer; (meningeal layer)

5. Arachnoid Mater
• It forms a loose investment for the
brain
• Connected by delicate connective
tissue with both the dura and pia
mater
• The delicate arachnoid layer is
attached to the inside of dura and
surrounds the brain and spinal cord
• Cerebrospinal fluid (CSF) flows
under the arachnoid in the
subarachnoid space

6. Pia Mater
• Thin fibrous tissue impermeable to fluid
• This allows the pia mater to enclose
cerebrospinal fluid
• By containing this fluid the pia mater
works with the other meningeal layers to
protect and cushion the brain
• Allows blood vessels to pass through and
nourish the brain
• The perivascular space created between
blood vessels and pia mater functions as a
lymphatic system for the brain

7. • In conjunction with the other meningeal membranes, pia mater functions to cover
and protect the (CNS), to protect the blood vessels and enclose the venous sinuses
near the CNS, to contain the (CSF) and to form partitions with the skull
• The CSF, pia mater, and other layers of the meninges work together as a protection
device for the brain, with the CSF often referred to as the fourth layer of the
meninges
Pia Mater

8. Subarachnoid space

9. Meninges of Spinal Cord

10. Cerebrospinal Fluid
• CSF is a clear, watery fluid that fills the ventricles of the brain and the
subarachnoid space around the brain and spinal cord.
• It also carries oxygen, glucose and other needed chemicals from the blood to
neurons and neuroglia.
• CSF continuously circulates through cavities in the brain and spinal cord and
around the brain and spinal cord in the subarachnoid space.

11. Ventricles of Brain

12. Lateral ventricle-
Located in each hemisphere of the cerebrum
Third ventricle-
Narrow cavity along the midline superior to the hypothalamus and between the right
and left halves of the thalamus.
Fourth ventricle-
Lie between the brain stem and the cerebellum

13. Functions of CSF
1. Mechanical Protection
2. Chemical Protection
3. Circulation